WiFi (for Wireless Fidelity also referred to as IEEE 802.11) is now fully integrated in the communication landscape and is becoming the dominant Wireless Local Area Networking (WLAN) standard. Developed in different versions (i.e. 802.11a/b/g/n) offering coverage up to hundreds of meters with a theoretical throughput up to about 50 Mbps, WiFi networks are widely deployed by means of numerous WiFi Access Points (AP) scattered across different environments including business, public and residential environments.
While roaming within the range of a WiFi access point, a mobile device equipped with a WiFi interface may remain constantly connected, through this access point, to wide-area networks (such as Internet or Intranet) for different communication services including delay-constrained ones (such as voice-over-IP, IPTV, or streaming).
However, as soon as the mobile device leaves the coverage of this WiFi access point, an interruption occurs, causing the loss of the WiFi network connection. Therefore, handover techniques for maintaining seamless connections during mobility are proposed so that, while moving, WiFi users do not experience substantial interruption in their ongoing communications via WiFi access points.
Nevertheless, although different solutions have been proposed to improve the handover process between WiFi access points, the handover triggering is often based on radio strength measurements (such as Signal to Interference and Noise Ratio SINR, or Received Signal Strength RSS). In fact, when the radio strength level becomes lower than a predefined threshold, the mobile station may either roam to another WiFi access point or switch the current WiFi connection(s) to another network offering a better connectivity (LTE for instance).
Such solutions lack robustness because radio strength measurements are not precise enough and generally depend on hardware platform. Moreover, radio strength level may decline quickly due to attenuation and fading (notably, because of multi-path propagation) with the risk for the mobile station to not having enough time to move current WiFi connection(s) on another radio network without interruption thereof.
One object of the present invention is to propose a method and algorithm to anticipate WiFi connectivity loss between a mobile station and a WiFi infrastructure in order to make all necessary actions to save or move existing network streams to another network that proposes a better connectivity.
Another object of the present invention is to provide a method for intra-WiFi access points handover for a seamless mobility.
Another object of the present invention is to provide an efficient trigger for intra-WiFi handover.
Another object of the present invention is to propose a metric for intra-WiFi access points handover that provides gains in term of delays and system overall throughput.